class_docstr: Performs streamlines tractography after selecting the appropriate algorithm.
  
  References
  ----------
  
  .. [FACT] Mori, S.; Crain, B. J.; Chacko, V. P. & van Zijl,
    P. C. M. Three-dimensional tracking of axonal projections in the
    brain by magnetic resonance imaging. Annals of Neurology, 1999,
    45, 265-269
  
  .. [iFOD1] Tournier, J.-D.; Calamante, F. & Connelly, A. MRtrix:
    Diffusion tractography in crossing fiber regions. Int. J. Imaging
    Syst. Technol., 2012, 22, 53-66
  
  .. [iFOD2] Tournier, J.-D.; Calamante, F. & Connelly, A. Improved
    probabilistic streamlines tractography by 2nd order integration
    over fibre orientation distributions. Proceedings of the
    International Society for Magnetic Resonance in Medicine, 2010, 1670
  
  .. [Nulldist] Morris, D. M.; Embleton, K. V. & Parker, G. J.
    Probabilistic fibre tracking: Differentiation of connections from
    chance events. NeuroImage, 2008, 42, 1329-1339
  
  .. [Tensor_Det] Basser, P. J.; Pajevic, S.; Pierpaoli, C.; Duda, J.
    and Aldroubi, A. In vivo fiber tractography using DT-MRI data.
    Magnetic Resonance in Medicine, 2000, 44, 625-632
  
  .. [Tensor_Prob] Jones, D. Tractography Gone Wild: Probabilistic Fibre
    Tracking Using the Wild Bootstrap With Diffusion Tensor MRI. IEEE
    Transactions on Medical Imaging, 2008, 27, 1268-1274
  
  Example
  -------
  
  >>> import nipype.interfaces.mrtrix3 as mrt
  >>> tk = mrt.Tractography()
  >>> tk.inputs.in_file = 'fods.mif'
  >>> tk.inputs.roi_mask = 'mask.nii.gz'
  >>> tk.inputs.seed_sphere = (80, 100, 70, 10)
  >>> tk.cmdline                               # doctest: +ELLIPSIS
  'tckgen -algorithm iFOD2 -samples 4 -output_seeds out_seeds.nii.gz -mask mask.nii.gz -seed_sphere 80.000000,100.000000,70.000000,10.000000 fods.mif tracked.tck'
  >>> tk.run()                                 # doctest: +SKIP
code: def _list_outputs(self):
      outputs = self.output_spec().get()
      outputs["out_file"] = op.abspath(self.inputs.out_file)
      return outputs
  
file_path: nipype/nipype/interfaces/mrtrix3/tracking.py
imports: import os.path
  from ..base import traits, TraitedSpec, File
  from .base import MRTrix3BaseInputSpec, MRTrix3Base
label_desc: Use image node_id 2 for calling the Tractography obj's underlying member method code with example usage: obj._list_outputs() and returns: outputs